Your conversational rules

An interesting thought experiment! What are a couple of rules that you wish more people would follow, to make conversations more fun?

As an example, here are two from Jeremy ~20 years ago:

1. Don't let the other one get away with saying something stupid or thoughtless -- unless, of course, that person is venting, or ponderously denouncing the entire population of (America, the human race, Business Majors, the people in the house next door, etc.), since logical dissection of this kind of talk would be missing the point.
2. If you don't understand, make the person explain.

Here are two from me:

1. Never navigate conflict by telling someone they know something, e.g. "Why won't you let me use your car? You know I'm a good driver."
2. If you have the option of making a fine logical point, or making some an appalling pun, go with the pun at least half the time.

What's your short list?